This invention relates to leak detection and more particularly to a leak detection system for deployment within a pipe.
Access to clean, potable water is of critical importance to all communities across the globe. Water scarcity is projected to be a growing problem for developing regions and industrialized nations alike. Even well developed regions with ample water supplies may encounter water shortages in the future due to population growth, climate change, and aging infrastructure. Water supply and water supply distribution are critical to a community's well being, and their role in addressing future needs of the world's cities and population will only grow in upcoming years.
In addition to accessing and treating water supplies, effective and efficient transportation of water from the water utility to consumer is critical in the management and distribution of water to its needed destination. Inefficiencies due to losses such as leaks in the distribution system have multiple negative impacts including energy and effort wasted for accessing and treating the water as well as the water itself. As the demand for clean water rises, water less due to inefficiencies in the distribution system threaten the water supplier's ability to meet demand. As access to existing and new sources of freshwater diminish, addressing water losses during distribution could replace the need to access new sources. Further wore in cases where water supply meets demand despite distribution waste and inefficiency, the energy and cost of accessing and purifying water sources into clean drinking water represent significant monetary and energy waste.
Water losses in USA municipalities typically range from 15 to 25 percent1. Superscript numbers refer to the references included herewith. The contents of all of these references are incorporated herein by reference in their entirety. The Canadian Water Research institute reports that on average, 20 percent of treated water is wasted due to losses during distribution and other unaccounted means2. Some unaccounted water losses include metering errors, accounting errors and theft; however, typically the greatest contributor to lost water is caused by leaks in the distribution pipes3. Clean water losses due to leaks represent a significant portion of the water supply.
A wide variety of approaches exist for detecting water leaks in pipes. At the most simplistic and basic level, the difference between the amounts of water produced by the water utility and the total amount of water recorded by water usage meters indicates the amount of unaccounted water. Larger values of unaccounted water almost certainly indicate losses due to leaks. More sophisticated methods for measuring and localizing water leaks in distribution pipes include acoustic methods where listening devices identify water leaks via characteristic sounds that indicate the presence of a water leak. In Direct Listening methods a trained technician surveys an area by moving a listening device around on the surface above a buried water pipe. The listening device transmits sound to the technician, and the technician listens for sounds consistent with a leaking pipe. Correlation methods use two listening devices placed at different locations along a distribution pipe and compare the acoustic signals to not only identify the presence of a leak, but also calculate the location between the listening devices based on the time delay between the two devices. Acoustic methods have also been extended to devices that operate inside the pipe to detect water leaks including the Sahara system4, which also detects leaks based on characteristics found in the acoustic signal.
While newer technologies have successfully moved acoustic methods to inside the pipe sensing, acoustic methods were born from the need to sense leaks from outside of the pipe. With new technologies to deliver sensor hardware to the interior of an active pipe network, non-acoustic methods can offer better sensing opportunities that were not available when out-of-pipe sensing was the predominant method for leak detection.
An object of the invention is thus an in-pipe leak detection system that includes structure capable of moving along the inside of a pipe and responsive to leaks in a wall of the pipe, or to leaks at pipe joints, pipe connections and valves.